Advances in electronics and technology have made it possible to incorporate a variety of advanced features on automotive vehicles. Various sensing technologies have been developed for detecting objects in a vicinity or pathway of a vehicle. Such systems are useful for parking assist and cruise control adjustment features, for example.
More recently, automated vehicle features have become possible to allow for autonomous or semi-autonomous vehicle control. For example, cruise control systems may incorporate LIDAR (light detection and ranging) for detecting an object or another vehicle in the pathway of the vehicle. Depending on the approach speed, the cruise control setting may be automatically adjusted to reduce the speed of the vehicle based on detecting another vehicle in the pathway of the vehicle.
There are different types of LIDAR systems. Flash LIDAR relies upon a single laser source to illuminate an area of interest. Reflected light from an object is detected by an avalanche photodiode array. While such systems provide useful information, the avalanche photodiode array introduces additional cost because it is a relatively expensive component. Additionally, the laser source for such systems has to be relatively high power to achieve sufficiently uniform illumination of the area of interest.
Scanning LIDAR systems utilize different components compared to flash LIDAR. One challenge associated with previously proposed scanning LIDAR systems is that additional space is required for the scanning components and there is limited packaging space available on vehicles. Optical phase array LIDAR systems utilize beam multiplexing that tends to introduce relatively significant power loss. Liquid crystal waveguides have even lower efficiency. In either case additional optical components are required for alignment and highly precise alignment accuracy is necessary.
Other aspects of previously proposed LIDAR systems include drawbacks. For example, two-dimensional scanning MEMS (micro-electro-mechanical system) mirrors are not suitable for use in environments subject to vibrations, such as automotive applications. Although one-dimensional MEMS mirrors are robust against vibrations they require multiple laser sources and respective mirrors to achieve an adequate field of view. The duplication of components in such systems increases cost and size requirements, both of which are considered undesirable.
There is a need for improvements in components for systems, such as LIDAR systems, that are lower-cost, easier to fit within small packaging constraints, and utilize power efficiently.